When it comes to hydration, there is much more to know than just “drink water.” You’ve probably read about losing salt in your sweat and the dangers of drinking too much water—but we’ve broken down these two important parts of hydration so you’ve got all of the facts.
The Salt Connection
Losses of sodium chloride (aka salt) in our sweat are always the highest and most variable depletions—and the longer you sweat, the greater your electrolyte losses. If you’re a “salty sweater,” you might notice white salt streaks on your clothing and skin after a tough workout. However, as you adapt to warmer weather, the sodium lost in your sweat can decrease. Sodium sweat losses can lead to muscle cramping, fatigue and increased risk of heat-related problems particularly when running for two hours or more.
Too Much Of A Good Thing
Hyponatremia occurs when sodium levels in your blood dip too low. This condition, relatively common in long distance runners, can result in side effects as annoying as nausea and as serious as death. While you might think the cause is heavy sweating, it’s actually over-drinking. Whether you replace sweat losses with plain water or a sports drink, consuming an amount of fluid in excess of your sweat losses can cause hyponatremia.
Monique Ryan is a Chicago-based nutritionist and author of Sports Nutrition for Endurance Athletes, 3rd Edition.